[uClibc] buildroot and other questions

[Ralph Siemsen]

Szekely Gyorgy wrote:

> Floating points.
> I'm using a PXA255 processor in a project, no FPU. I compiled the NWFPE 
> in the kernel, but I've read somewhere that this is slow because the 
> processor generates an exception at every FP instruction. If gcc 
> compiles calls to the floating point functions directly is a bit faster. 

NWFPE isn't quite that bad - successive FP operations will be done with 
a single exception.  But still, software-float is much better/faster. 
When you tell gcc "-msoft-float" then it will make a function call for 
all float operations instead of putting in FP opcodes.  You then have to 
provide a libfloat where these functions are defined.  Fortunately, in 
gcc-3.4 this is already included.

With buildroot you need only select "Use software floating point by 
default" (no need for libfloat as its inside gcc now).  You can then 
take our NWFPE from your kernel config if you like, as nothing should be 
using it.

> What's multilib? Do I need it? (same project)

No.  Its for mixed 32/64 bit library support.

> What's armeb?

That's big-endian ARM.

-Ralph